The main challenges with battery SoH indicator methods are the different varieties of battery types and chemistries, with different rated capacities and nominal voltages. Since a battery's response to a discharge pulse used for testing is highly dependent on the above variables, existing testing methods are typically offered for only a specific battery type and model. Furthermore, a large quantity of test data for the specific model's response is pre-processed.
U.S. Pat. No. 6,441,585 to Bertness discloses a system that measures an open circuit voltage and a dynamic parameter of a test battery, and uses those measurements, along with correlation data stored in memory, to determine a physical condition and/or charge state of the battery. The measured dynamic parameter may be scaled based on the rating of the test battery. Also, a high current load pulse may be applied to the test battery and a wait period implemented before the open circuit voltage is measured. In addition, the charge state may be determined from a state of charge value, and categorized into one of several charge state ranges.
U.S. Pat. No. 7,619,417 to Klang discloses a battery monitoring system, which utilizes a minimum amount of input data (time, voltage, current, temperature and conductance, for example) to periodically determine a vehicle battery status or condition. The battery is projected to standard conditions with which it can be compared directly with the original ratings of the battery for cranking performance and capacity.
U.S. Patent Application Publication No. 2003/0184307 to Kozlowski discloses a model-based predictive diagnostic tool for primary and secondary batteries. Determining a condition parameter of a battery includes the step of obtaining condition data correlated with the condition parameter. The method includes the step of providing the condition data to a plurality of prediction algorithms, wherein each prediction algorithm provides a condition parameter estimate. The method also includes determining the condition parameter using the plurality of condition parameter estimates.
U.S. Patent Application Publication No. 2011/0172939 to Uprety discloses a system and method for determining an internal resistance, SoC, SoH and battery energy level of a rechargeable cell or battery pack. The system includes a current, voltage, and temperature sensor. The system includes a processor that is configured to read a first bulk current of the battery at a first time, and, when the first bulk current is less than a first threshold, read a second bulk current at a second time. When the second bulk current has a value between a second threshold and a third threshold and the difference between the first time and the second time is less than a pre-determined delay threshold, the processor is configured to use the first and second bulk current values to determine an internal resistance of the battery or cell.
This background information is provided to reveal information believed by the applicant to be of possible relevance to the present invention. No admission is necessarily intended, nor should be construed, that any of the preceding information constitutes prior art against the present invention.